2171489665 has 4 divisors (see below), whose sum is σ = 2605787604. Its totient is φ = 1737191728.

The previous prime is 2171489647. The next prime is 2171489717. The reversal of 2171489665 is 5669841712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1433606769 + 737882896 = 37863^2 + 27164^2 .

It is a cyclic number.

It is not a de Polignac number, because 2171489665 - 2⁹ = 2171489153 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 217148962 + ... + 217148971.

It is an arithmetic number, because the mean of its divisors is an integer number (651446901).

Almost surely, 2^2171489665 is an apocalyptic number.

It is an amenable number.

2171489665 is a deficient number, since it is larger than the sum of its proper divisors (434297939).

2171489665 is an equidigital number, since it uses as much as digits as its factorization.

2171489665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434297938.

The product of its digits is 725760, while the sum is 49.

The square root of 2171489665 is about 46599.2453265072. The cubic root of 2171489665 is about 1294.9487743287.

The spelling of 2171489665 in words is "two billion, one hundred seventy-one million, four hundred eighty-nine thousand, six hundred sixty-five".